Nanosensor rapidly detects presence of pathogenic E. coli strain

Magnetic resonance and fluorescence methods have been combined in one nanosensor for the ultra-sensitive detection of Escherichia coli O157:H7

Researchers have developed a new nanosensor to rapidly detect the presence of a pathogenic strain of E. coli.

More than 1,000 deaths every year in the US are attributable to foodborne illness caused by known pathogens, according to the US Centers for Disease Control and Prevention. But identifying the foodborne pathogen causing the sickness in many instances can be a slow process.

Conventional methods to screen food to find sickness-causing microbes can take as long as 24 hours, which is often too slow to efficiently catch tainted products before they hit store shelves.

Faster methods exist, but have limitations. Magnetic resonance, for example, can detect extremely low levels of bacteria, but loses its effectiveness at higher bacteria concentrations. Fluorescence is the opposite.

Tuhina Banerjee, Santimukul Santra and colleagues from the Department of Chemistry, Kansas Polymer Research Center, Pittsburg State University, wanted to see if they could combine the two techniques to make a better detector.

For a new study the researchers developed a hybrid nanosensor incorporating magnetic resonance and fluorescence.

Their study, published in the journal ACS Infectious Diseases, says lab testing of milk showed the detector could sense varying concentrations of a pathogenic strain of E. coli O157:H7 in less than an hour.

They also used the sensor to analyze E. coli levels in untreated lake water, which serves as a source of household water in some developing areas.

Additionally, the researchers say the device could be customised to detect a wide range of pathogens beyond E. coli.

The authors acknowledge funding from the Kansas Soybean Commission and Pittsburgh State University.

For details visit http://pubs.acs.org/doi/abs/10.1021/acsinfecdis.6b00108